The present invention relates to a semiconductor device having a fluorine-added carbon dielectric film and a method of fabricating the semiconductor device.
Finer patterns and multi-layered circuitry have been advanced for higher integration of semiconductor devices. One of the techniques is multilevel interconnection structure which an n-wiring layer and an (n+1)-wiring layer are connected via a conductive layer with a thin interlayer dielectric film.
One representative of the interlayer dielectric film is an SiO2 film having a specific dielectric constant of about 4. Efforts have been made however for discovering materials having smaller specific dielectric constants for faster semiconductor devices. A choice is SiOF films having a specific dielectric constant of 3.5.
The inventors of the present invention have focused on fluorine-added carbon films having a much smaller specific dielectric constant. The fluorine-added carbon film is termed a CF film herein after.
Semiconductor device structures having a CF-dielectric film requires a wiring layer of aluminum (Al), for example, formed on the CF-dielectric film and tungsten (W) wiring for connecting an n-stage Al layer and an (n+1)-stage Al layer. Electromigration would however occur on Al layers to cut off the layers when a current flows therethrough. A titanium nitride (TiN) layer as a reinforcing material for the Al layer and a Ti layer formed between the TiN layer and CF film have been under consideration.
However, CF films are similar to polytetrafluoroethylene, and have a low level of adhesiveness. Deposition of W wiring heats the CF film to about 400xc2x0 C., for example, to cause evaporation of the interface between the CF film and Ti layer, thus resulting in that the CF film is peeled off from the Ti layer.
Semiconductor device structures having a CF film as an interlayer dielectric film have therefore not been achieved so far for practical application.
A purpose of the present invention is to provide a semiconductor device formed with a metallic layer on a fluorine-added carbon film, in which fluorine-added carbon film and the metallic layer are protected from being peeled-off from each other and a method of fabricating such a semiconductor device.
The present invention provides a semiconductor device having a dielectric film made of a fluorine-added carbon film formed on a substrate, a metallic layer formed on the fluorine-added carbon film and an adhesive layer formed between the dielectric film and the metallic layer. The adhesive layer is made of a compound layer including carbon and the metal (or metal the same as the metal included in the metallic layer), to protect the metallic layer from being peeled-off from the fluorine-added carbon film.
Moreover, the present invention provides a method of fabricating a semiconductor device. A dielectric film made of fluorine-added carbon film is formed on a substrate, and fluorine included in a surface of the fluorine-added carbon film is decreased in density. A metallic layer is formed on the surface of the fluorine-added carbon film. An adhesive layer made of a compound layer including carbon and metal the same as metal included in the metallic layer is formed between the fluorine-added carbon film and the metallic layer. After fluorine is decreased in density, while forming a metallic layer on a surface of the fluorine-added carbon film or heating the substrate after the metallic layer is formed, an adhesive layer made of a compound layer including carbon and the metal may be formed between the fluorine-added carbon film and the metallic layer. Moreover, after fluorine is decreased in density, a metallic layer may be formed on a surface of the fluorine-added carbon film by chemical vapor deposition using a deposition gas including metal, to form an adhesive layer made of a compound layer including carbon and the metal between the fluorine-added carbon film and the metallic layer.